sleeping_barber.py

from threading import Thread, Lock, Event
import time, random

mutex = Lock()

#Interval in seconds
customerIntervalMin = 5
customerIntervalMax = 15
haircutDurationMin = 3
haircutDurationMax = 15

class BarberShop:
    waitingCustomers = []

    def __init__(self, barber, numberOfSeats):
        self.barber = barber
        self.numberOfSeats = numberOfSeats
        print 'BarberShop initilized with {0} seats'.format(numberOfSeats)
        print 'Customer min interval {0}'.format(customerIntervalMin)
        print 'Customer max interval {0}'.format(customerIntervalMax)
        print 'Haircut min duration {0}'.format(haircutDurationMin)
        print 'Haircut max duration {0}'.format(customerIntervalMax)
        print '---------------------------------------'

    def openShop(self):
        print 'Barber shop is opening'
        workingThread = Thread(target = self.barberGoToWork)
        workingThread.start()

    def barberGoToWork(self):
        while True:
            mutex.acquire()

            if len(self.waitingCustomers) > 0:
                c = self.waitingCustomers[0]
                del self.waitingCustomers[0]
                mutex.release()
                self.barber.cutHair(c)
            else:
                mutex.release()
                print 'Aaah, all done, going to sleep'
                barber.sleep()
                print 'Barber woke up'
    
    def enterBarberShop(self, customer):
        mutex.acquire()
        print '>> {0} entered the shop and is looking for a seat'.format(customer.name)

        if len(self.waitingCustomers) == self.numberOfSeats:
            print 'Waiting room is full, {0} is leaving.'.format(customer.name)
            mutex.release()
        else:
            print '{0} sat down in the waiting room'.format(customer.name)  
            self.waitingCustomers.append(c) 
            mutex.release()
            barber.wakeUp()

class Customer:
    def __init__(self, name):
        self.name = name

class Barber:
    barberWorkingEvent = Event()

    def sleep(self):
        self.barberWorkingEvent.wait()

    def wakeUp(self):
        self.barberWorkingEvent.set()

    def cutHair(self, customer):
        #Set barber as busy 
        self.barberWorkingEvent.clear()

        print '{0} is having a haircut'.format(customer.name)

        randomHairCuttingTime = random.randrange(haircutDurationMin, haircutDurationMax+1)
        time.sleep(randomHairCuttingTime)
        print '{0} is done'.format(customer.name)


if __name__ == '__main__':
    customers = []
    customers.append(Customer('Bragi'))
    customers.append(Customer('Auja'))
    customers.append(Customer('Iris'))
    customers.append(Customer('Axel'))
    customers.append(Customer('Andrea'))
    customers.append(Customer('Agnar'))
    customers.append(Customer('Mamma'))
    customers.append(Customer('Solla'))
    customers.append(Customer('Olla'))
    customers.append(Customer('Berglind'))
    customers.append(Customer('Bergdis'))
    customers.append(Customer('Margret'))
    customers.append(Customer('Brynjar'))
    customers.append(Customer('Siggi'))
    customers.append(Customer('Tomas'))
    customers.append(Customer('Kristrun'))
    customers.append(Customer('Heidrun'))

    barber = Barber()

    barberShop = BarberShop(barber, numberOfSeats=3)
    barberShop.openShop()

    while len(customers) > 0:
        c = customers.pop() 
        #New customer enters the barbershop
        barberShop.enterBarberShop(c)
        customerInterval = random.randrange(customerIntervalMin,customerIntervalMax+1)
        time.sleep(customerInterval)